Short answer
Oral HRT is linked to more blood clots, but the extra risk is small. In a Danish study of women 50 to 69 (The BMJ, 2026), oral estrogen added about 0.09% a year in absolute risk of a vein clot, roughly one extra clot for every 1,055 women using it for a year. Patches and gels showed no increase.
Relative risk versus your actual risk
Headlines usually quote relative risk: oral estrogen was linked to a 1.6 times higher rate of clots in veins. That sounds large. The absolute numbers are what matter for a decision.
Among Danish women aged 50 to 69 not using hormone therapy, about 15.8 in 10,000 developed a vein clot each year. Oral therapy added roughly 0.09 percentage points a year. The study's number needed to harm was 1,055: about one extra vein clot for every 1,055 women using oral therapy for a year.
Strokes and heart attacks
The same study found smaller absolute increases for ischemic stroke (about 0.06% a year, one extra per 1,642 women) and heart attack (about 0.03% a year, one extra per 3,846). Risk rose with dose and time: oral estradiol above 1 mg a day for more than five years carried about 1.8 times the rate of stroke and of heart attack.
Transdermal patches and gels were not linked to higher clot or stroke rates, with one exception: combined cyclic patches and heart attack.
Who should ask more questions
The study excluded women with a past clot, cancer, liver disease or a known clotting disorder, so its numbers describe lower-risk women. If any of those apply to you, or you smoke or have heart disease, your risk picture is different and worth a direct conversation with your clinician.
The study was observational and from one country. It is strong on scale, weaker on proving cause. Educational content, not medical advice.
Related questions
Does the clot risk depend on dose or how long you take it?
For vein clots, the BMJ study found oral therapy was linked to higher risk regardless of dose and duration. For stroke and heart attack, risk rose with long use of oral estradiol above 1 mg a day.
Should I stop HRT because of this?
Not on your own. Stopping can bring symptoms back. Bring the numbers to your clinician and ask whether your dose and route fit your risk.
Read next
Sources
Published 2026-10-03 · Last checked 2026-10-03
Educational content, not medical advice. Made for the United States.